The overall goal of this research is the design, development and in vivo testing of a type I collagen based ligament template to support the regeneration of the anterior cruciate ligament (ACL) of the knee joint. The collagen ligament template is biocompatible, bioresorbable and is fabricated from natural connective tissue components. During phase I, we will define the procedure for extruding collagen filaments from highly purified bovine Achilles tendon collagen fibers, develop a prototype and test the prototype in vivo for healing response. During the past 20 years of development of an ACL prosthesis the general conclusion has been that a permanent replacement of an ACL with a non-degradable polymer cannot fulfill the function as a long term ACL substitute. The concept of ACL reconstruction using a resorbable collagen template, made of extruded collagen filaments, to support the ligament regeneration has not yet been tested. We believe a carefully designed collagen template has the potential to function as a temporary ligament substitute while supporting the host to regenerate its own ligament. Nearly 110,000 ACL injuries per year in the US alone and greater than one- third of the injured patients require repair or reconstruction. ACL reconstructions is generally performed by autografting (bone-patellar tendon-bone). In addition to the creation of a second injury site, autografting often results in pain and strength loss in the quadriceps and requires extended rehabilitation times. There is no ideal method that ensures the restoration of a normal functioning ACL.